ABSTRACT
The Ministry of Construction of the Japanese Government carried out research into the utilization of wastes from construction works, and the development of reuse techniques for demolished concrete was one of the main subjects. After some feasibility studies, recycled aggregate was taken up, as a coarse and fine aggregate extracted mechanically from demolished concrete. The results of laboratory-experiments for the properties of recycled aggregate and concrete with recycled aggregate, showed that the specific gravity and absorption were affected by the amount of cement paste which was sticking on the aggregate and as the soundness of aggregate was related to absorption, the properties of concrete with recycled aggregate with high absorption tended to be worse in strength and in resistance to freezing and thawing than those with ordinary aggregate. The field tests showed no problems in the mixing, placing, and compaction procedures. Some recommendable usages for concrete with recycled aggregate were also proposed by considering the experimental results and expenses for refinning the aggregate.
